The invention relates to an implantation device for treating damaged or diseased tissue in the region of the inner walls of hollow organs, and in particular to an implantation device for treating a dissection in body vessels, with a catheter and at least one fastening means connected with said catheter, whereby the catheter has a long-stretching hollow body which is open at least at its front end when employed as intended, and in which each fastening means is received with axial mobility when the implantation device is inserted in the vessel of the body.
Such an implantation device is known from EP-A-466 518 even though said device is not intended for treating vessels of the body.
Said known implantation device is a device for implanting an artificial blood vessel, which is implanted by means of a catheter in the correct position and expanded in the site of implantation. For this purpose, the artificial blood vessel is received during the implantation in a constricting covering, which is removed after the implantation. The artificial blood vessel is provided with spring elements which, in turn have barbs that get hooked up in the site of implantation, and in this way maintain the artificial blood vessel elastically in its desired position, expanding it to some extent as desired. Owing to the fact that the elastic fastening means are connected with the artificial blood vessel and, to that extent, in each case indirectly also with the catheter, exact positioning of the fastening means as deemed desirable, for example for treating dissections, but also in connection with other applications, is not possible. In connection with the object of EP-A-466 518, the fastening means are rather connected with the artificial blood vessel in a fixed manner. Therefore, it is not possible with said known implantation device to implant the fastening means as such.
A method and a device for securing a graft in the lumen of a body vessel are known from U.S. Pat. Ser. No. 4,872,874.The known device comprises a catheter with an expandable balloon segment at its distal end. The balloon segment is provided with a U-shaped annular groove, in which staples as securing means are distributed over the circumference and receivable with legs connected with each other via a bridge in such a way that the free ends of the legs point outwardly. By means of said device, a graft first introduced in a body vessel can be secured on vascular walls by positioning the balloon segment with the annular groove receiving the securing means, said balloon segment being inserted in the vessel in its expanded condition and being provided with securing means, within the proximity of one end of the graft, and by subsequently inflating the balloon segment. In this process, the radially protruding legs of the staples have to pierce the graft and penetrate the vascular wall in order to keep the graft attached to the vascular wall after the balloon segment has been deflated.
However, it has been found that the legs of the staples serving as securing means easily assume a slanted position when the balloon segment is expanded, or only inadequately penetrate the vascular wall. This can be assumed to be attributable to the fact that the depth of the annular groove serving for receiving the securing means becomes progressively smaller, causing the securing means to lose their guidance. As a result thereof, the graft is only inadequately tacked to the vascular wall, and, furthermore, damage may be caused to the vascular wall.
In the known device, the balloon segment of the catheter is considerably widened radially even when it is in its unexpanded condition, so that this implantation device can be employed on with larger body vessels.
Accordingly, the invention is based on the problem of creating an improved implantation device of the type and for the purpose specified above. Such device permits strictly local treatments of damaged or diseased tissue of the inner walls of hollow organs while reducing at the same time the stress to which the tissue is subjected to in such treatments.
Said problem is solved in that the implantation device as defined in the introductory part of claim 1 comprises a catheter with a long-stretched hollow body, which is open at least at its front end when used as intended, and in which one or a plurality of securing means are received with axial mobility. The application of such a catheter requires only a small cross section for its insertion. Such a catheter is, therefore, suitable also for vessels with a small lumen. After the catheter has been placed in its correct position, the securing means received therein is expelled from the catheter and implanted in the vascular wall.
The implantation device thus comprises a catheter in which one or several securing means are received when it is introduced in the body vessel. Following placement of the catheter in its appropriate position within the region of the site of the diseased tissue, for example on a dissecate, said securing means are advanced from the catheter and implanted in the vascular wall. In case of a dissecate, the treatment is carried out in a simple fashion in that the dissecate is tacked to the vascular wall with the help of the securing means. The implantation device as defined by the invention therefore assures that the treatment of the dissecate is precisely xe2x80x9con targetxe2x80x9d. The tissue is stressed only within the immediate proximity of the securing means and the stress to which the tissue of the organ is subjected to is consequently reduced to a minimum. With larger dissecates, the application of several securing means is recommended, which have to be implanted spaced from each other.
The possibilities available for employing the implantation device as defined by the invention extend far beyond the treatment of vascular diseases and may comprise also, for example the treatment of detachments of the retina, by reliably and permanently connecting the latter with the choroid with the help of securing means. As opposed to currently applied coagulation therapies, which only permit a prophylactic treatment of endangered regions, the treatment with the help of the implantation device as defined by the invention also permits reattachment by tacking on areas of the retina that have become detached.
Treatment possibilities are expanded in that means for receiving and positioning a protective cover for the affected tissue are arranged on the catheter. It is possible with the help of the protective cover to treat also large areas of the tissue regions, where the use of only securing means is inadequate or not possible. Covering the bag-like dilatation of the vessel with such a protective cover is recommended especially for the treatment of aneurisms, whereby the protective cover is tacked within the marginal region of the aneurism with securing means in the healthy tissue. As opposed to the conventional treatment with stents, the lumen of the vessel is not narrowed down and the risk of a stenosis due to formation of a neointima is largely reduced.
The type of protective covering to be used depends in this connection on the application in a given case. A useful protective covering is, for example a piece of textile or tissue adapted to the damaged area of the tissue. The fabric may consist of a stable or flexible material depending on the application. The use of a biodegradable material is recommendable for many applications. In particular, the use of the body""s own tissue or of a transplant is possible as well.
The present implantation device also permits tacking grafts to the inner wall of a body vessel. A supporting stent structure can be entirely omitted in this way. As opposed to conventional treatments with stents, the lumen of the body vessel is not noticeably reduced.
A nail adapted to the thickness of the wall of the hollow organ is a securing means that is adequate in many cases. The shaft of such a nail is inserted in the vascular wall. However, staples with two or more legs can be used as well depending on to which extent the affected region of the tissue is stressed, with the legs of such staples being arranged U- or V-shaped relative to each other. Also, the securing means may have two flexible legs, which are connected with each other with one of their ends. In the course of the implantation process, said legs are kept parallel with each other in the catheter and spread in the form of a xe2x80x9cVxe2x80x9d only as the catheter is being implanted, which keeps the cross section being used in the course of insertion of the catheter very small, on the one hand, and produces a reliable and fixed connection in the state of implantation on the other. Furthermore, the securing means can be fitted with barbs, which further increases the strength of the connection provided by the securing means.
It is very advantageous as well from case to case if a biodegradable material is used also for the securing means. If the securing means consist of an elastic material such as, for example, xe2x80x9cNitinolxe2x80x9d, the introduction of the catheter segment containing the securing means is facilitated if the body vessels are highly curved, and the risk of damage is reduced.
As an alternative to securing means consisting of solid materials, it is possible also to employ a material that is liquid in the course of implantation and squeezed out of the catheter, and hardens or cures in the implantation site after a certain period of time.
So that the treatment can be monitored in an optimal way, it is useful if the securing means is marked with diagnostic contrast media in order to facilitate monitoring of the surgical intervention, for example with the help of X-radiation or magnetic resonance. In order to avoid interference with the imaging in magnetic resonance tomography, a metal should be used in this connection that is not active ferromagnetically.
According to another advantageous development of the invention the securing means is suitable for receiving and dispensing a predetermined amount of medication in a controlled manner. This reliably assures that an optimal medicinal supply is available for locally limited damaged areas, for example in the treatment of ulcers or the like.
For receiving medications it is possible to consider, for example hollow spaces arranged in the securing means itself, which are either provided with apertures from which the medication exits in a controlled way, or which, when a biodegradable material is used, release the medication in the course of the degradation process of the securing means. Particularly when medications have to be used in greater amounts, it is useful if a medication pouch is attached with the help of the securing means within the immediate proximity of the diseased region. The medication pouch, which preferably consists of a biodegradable material, may have small apertures from which the medication exits at a predetermined release rate.
In order to facilitate the implantation of the securing means, the hollow body of the catheter is advantageously bent upwardly with its front end. Such upwardly bent configuration also effect an entirely desirable limited expansion of the body vessel in the course of implantation.
In another embodiment, the hollow body consists of an elastic material, so that such body is present in the long-stretched state as the catheter is being introduced in the body vessel, and its front segment is bent up in the direction of the vascular wall only after it has been placed in the vessel in its correct position. It is important in this connection that the inside cross section of the hollow body remains substantially the same as it is being bent in order to avoid that the securing means is canted in the hollow body, or not implanted in the body vessel in the intended way.
A simple yet effective possibility for implanting the securing means in the intended manner in the wall of the hollow organ is to receive a pusher with axial mobility in the hollow body of the catheter. When employed as intended, such pusher can be actuated at the proximal end of the catheter. At its front end, the pusher is actively connected with the securing means in such a way that that the securing means can be pushed out of the catheter with the help of the pusher and implanted in the wall of the organ.
In yet another embodiment of the invention, the securing means is designed in the form of a screw or spiral and has a coupling means on its rear segment for connecting it with torsional strength yet detachably with a corresponding coupling segment of the pusher. With such an embodiment, implantation is carried out as follows: after the catheter has been placed in its correct position, the securing means is screwed into the wall of the organ by actuating the pusher as required, and then detached from the pusher after it has been implanted.
According to another advantageous development of the invention, the hollow body of the catheter is received in a sleeve with at least part of its longitudinal expanse. The sleeve serves in this connection for the protection of the hollow body and, if the latter consists of a particularly flexible material, for stabilizing the catheter as it is being introduced in the hollow organ.
With catheters having a flexible hollow body, the front segment of the hollow body can be bent or deflected upwardly in a simple manner by a filament which, in its intended state, extends along the catheter and has its front end connected with the hollow body. The catheter, except for a predetermined front segment thereof, is stiffened by suitable means, for example by the aforementioned sleeve, so that only said front segment can be deflected or bent upwardly by actuating the filament.
In yet another embodiment, the filament extends in the interior of the hollow body in a second lumen in the wall of the catheter. In this embodiments the front segment is deflected upwardly in the way of a Bowden wire. Also, the filament may consist of a wire, in which case superior stability is obtained.
So that damage to the catheter and also to the vascular wall is avoided to the greatest possible extent, the segment to be deflected is provided with a reinforcement according to claim 25. Such reinforcement may be, for example a thin, flexible metal foil, which is arranged in this part of the hollow body of the catheter. Furthermore, the catheter may be completely made of metal such as, for example, xe2x80x9cNitinolxe2x80x9d.
In yet another embodiment, the securing means is actively connected with spring means, with whose help the securing means is inserted at high speed in the wall of the hollow organ and produces there a particularly reliable and solid connection, for example on a dissecate on the vascular wall. The spring means may be arranged within the hollow organ in the catheter and may be directly connected with the securing means. When the catheter is introduced in the hollow organ, the spring means are pretensioned, and are released by a suitable releasing device after the catheter has been placed in its appropriate position. This can be accomplished, for example by means of a pusher, which is guided through the hollow body of the catheter. It is possible also to mount the spring means at the proximal end of the catheter, thus outside of the body, and to transmit the spring forces to the securing means with the help of the pusher.
Instead of employing spring means it is possible also to use an electromagnetic drive, which is arranged outside of the body and which advances the securing means via the pusher over a predetermined distance. According to another alternative, provision is made that the securing means is driven into the wall of the hollow organ by means of ultrasonic waves, which are emitted by an ultrasound arrangement actively connected with the lumen of the hollow body of the catheter.
Usefully, several simultaneously implantable securing means are received in the hollow body. This is particularly advantageous when securing larger protective coverings or a hose-like graft.
According to yet another development of the invention, several securing means are arranged in associated receiving segments of the front part of the hollow body of the catheter. After the catheter has been appropriately positioned in the hollow organ, the various receiving segments are bent up independently of each other in the direction of the intended site of implantation and the securing means are subsequently driven in, preferably simultaneously.
So as to assure a rational and careful intervention, provision is made according to claim 31 for arranging a plurality of securing means one after the other in the hollow body of the catheter, so that a sequential implantation can be carried out This design is very advantageous particularly for the treatment of long-stretched dissecates.
According to another embodiment of the implantation device as defined by the invention, provision is made that a magazine with a plurality of securing means and a loading device are arranged on the catheter. After each implantation of a securing means, the loading device takes another securing means from the magazine and positions it in the site in the hollow body which was previously occupied by the now-implanted securing means. It is possible in this way to implant a great number of securing means in the course of one single intervention.
Alternatively to the magazine, provision is made according to claim 33 for elastically stretchable securing means, which are received laterally of the pusher in the hollow body of the catheter and/or in the sleeve of the catheter, and which, after a first securing means has been implanted, are pushed into the starting position of the implanted securing means with the help of suitable means, for example a loading pusher extending coaxially around the pusher, whereby such securing means automatically change into the intended form of implantation.
In yet another embodiment, the hollow body of the catheter is in connection with a feed hose, through which further securing means can be pushed in the hollow body of the catheter with the help of a separate feeding pusher. It is particularly advantageous in this connection that basically any desired number of securing means can be inserted without having to remove the catheter from the body vessel. However, in a similar way even the hollow body of the catheter itself can be employed as a feeding hose.
So as to achieve a satisfactory success of the treatment it is important that the tissue intended for implantation with a securing means is under pretension at the time of the surgical intervention. In the exemplified embodiment according to patent claims 14 to 34, such pretension is assured especially by the unbent front segment of the hollow body. In order to enhance the pretension, provision is made according to claims 35 and 36 for additional devices arranged on the catheter. The object according to claim 35 is a spreading sleeve consisting of bridges separated from each other by longitudinal slits. The spreading sleeve is inserted in the vessel with the catheter in the stretched condition, in which the bridges are arranged resting substantially parallel against each other. After the catheter has been placed in the correct position, the spreading sleeve is spread by means of a suitable pulling element in order to provide the vessel with the desired pretension. After the implantation is completed, the spreading sleeve is again changed into the stretched condition and removed from the vessel. According to claim 36, the catheter is actively connected with a balloon catheter which, after its expansion, also effects a uniform expansion of the entire vessel section. The implantation catheter extends partly within the spreading sleeve or the balloon catheter and is brought there into its intended position. In the case of the balloon catheter, implantation of the securing means can take place, for example through a predetermined opening in the sleeve of the balloon catheter.
In order to prevent the point or tip of the catheter or the securing means from sliding down on the wall of the hollow organ, provision is made according,to claim 37 that the front end of the catheter is pointed and, after the catheter has been placed in the right position, slightly penetrates the vascular wall, which substantially reduced the risk of letting it slide down.
If provision is made for means for receiving a protective covering on the catheter, it is particularly advantageous if such means can be controlled independently of each other, for example by means of suitable positioning wires. This permits positioning of the protective covering in the intended site with great accuracy.
If possible, the positioning wires should be arranged within separate channels in the wall of the catheter.
In yet another embodiment, the catheter has a probe made of a thin filament, on which a securing means designed at least in sections in the form of a hollow element is detachably received when the implantation device is in its inserted state. Such a design is especially useful with very narrow vessel cross sections. Such a probe, too, can be deflected upwardly with its front segment by means of a filament mounted on the probe, so that the securing means can be brought into a starting position preferred for its implantation. The catheter itself, which extends coaxially around the probe, serves in this connection for inserting the securing means in the vascular wall.
In another advantageous development of the invention, the implantation device is equipped with an ultrasound probe arranged on the catheter for image acquisition, such probe permitting direct monitoring of the region of the surgery.